1. Field of the Invention
The present invention relates to a vessel with a single hull, the aft part of which has a smaller water displacement and less breadth lying in the water than the middle or central part, and provided with a foil extending below the waterline.
2. Description of the Related Art
Vessels having foils or vane-like members situated under the aft portion of the hull are known in the prior art. In particular, planing vessels are sometimes provided near the end with a foil or flap extending below the hull, in order to ensure that during planing the trim angle that the hull forms with the surface of the water is limited. Such planing vessels generally have a hull displacement that does not change substantially from the middle part in the aft direction.
An example of such a construction is found in U.S. Pat. Nos. 2,832,304; 4,915,048 and the Abstract of Japanese Patent Application 62008893. In these cases the foil is situated on the aft end of the vessel, and a vertical lift force is generated. Such vessels have no constriction of the submerged part of the vessel, in other words the cross-section of the submerged part of the vessel (perpendicular to the direction of movement of the vessel) does not decrease in the aft direction.
Furthermore, some catamarans are provided with fins for the purpose of reducing ship movement in waves. Such fins do not always have a foil profile. An example of the use of these fins in a boat is found in U.S. Pat. No. 3,208,422.